Four-electrode tube



OC. 24, H' J, ROUND FOUR-ELECTRODE TUBE Filed June 16, 1927 INVENTORHENRY JOSEPH ROUND AT ORNEY Patented Oct. 24, 1933 Miren STATES PATENTOFFICE FOUR-ELECTRODE TUBE Application June 16, 1927, Serial No.199,170, and in Great Britain July 22, 1926 3 Claims.

This invention relates to four-electrode tubes, and more particularly tofour-electrode tubes of the lrind in which there is provided an outergrid acting as an electrostatic shield between an inner and a plate.

The present invention has for its object the provision of a tube of thekind referred to, which shall be simple to construct and which shall beconstructionally similar to as great a degree as possible, to the wellknown three-electrode 'tubes of the type in which there is provided afilament, a grid substantially surrounding the lament, and a platesubstantially surrounding the grid.

Briefly and broadly the object of this invention is to provide afour-electrode tube comprising a filament, an inner grid substantiallysurrounding the filament, an outer grid electrode substantiallysurrounding the inner grid, and one or more plate electrodes, said outergrid electrode being formed of a plate-like electrode having one or moreWindows filled with grid mesh parallel wires or the like therein, andplate electrode or electrodes being located substantially opposite thesaid window or windows. n

Preferably the plate electrode or electrodes is or are each slightlysmaller than its appropriate window in the outer grid electrode, and isor are supportedirom the support rods for the outer grid electrode,being, or" course, insulated therefrom.

The lead from the plate electrode or electrodes is passed through thebulb oi the tube, the usual four-pin base and connection and supportingarrangements being employed for the remaining electrodes. Thisarrangement of leads has the considerable advantage that the lead fromthe plate or plates is comparatively far removed from the other leads,so that the electrostatic coupling between the input and output circuitsof the valve is reduced to a very small value.

These and other advantages and objects of the invention will become moreapparent, from the specification when read in connection with theherewith appended drawing on which:

Fig. 1 is an elevation of a tube constructed in accordance with myinvention, and

Fig. 2 is a plan view of the tube shown in Fig. 1.

Referring to this drawing, 1 is a hair-pin lilament supported upon leads2 and a filament support 3. 4l is an inner grid carried upon supports 5.6 is an outer grid electrode formed of a platelike electrode, having apair of oppositely disposed windows 7, cut in its at sides, the saidwindows being lled with grid mesh parallel Wires, cross Wires or thelike. The electrode 6 is (Cl. Z-27.5)

carried by support rods 8. 9, are plates smaller in area than theWindows 'l and carried by means of yokes 10, supported on and insulatedfrom the support rods 8 by means or" glass beads 11. The lead 12 fromthe plates 9 is passed through the 60 side of the bulb 13 of the tube,the connections for the other electrodes being passed through the stem14 to a four-pin base (not shown) in the usual way.

Having now particularly described and illustrated the nature of my saidinvention and in What-manner the same is to be performed, what claim is:

1. A thermionic valve comprising a lament, an inner grid surrounding thefilament, an outer grid electrode surrounding the inner grid, and plateelectrodes, said outer grid electrode being formed of a plate-likeelectrode having windows iilled with grid mesh parallel wires, and saidplate electrodes being located opposite to the said windovvs.

2. A thermionic valve comprising a filament, an inner grid surroundingthe iilament, an outer grid electrode surrounding the inner grid, and aplate electrode, said outer grid electrode being formed or" a plate-likeelectrode having a Window filled with grid mesh, and said plateelectrode being smaller than the window and located opposite thereto.

3. An electron discharge device comprising a cathode, an inner attenedcylindrical grid electrode surrounding the cathode, an outer attenedcylindrical grid electrode surrounding the inner grid electrode, theattened portions of the outer grid electrode being provided Withopenings covered with grid mesh material, and a pair of plate electrodesexternal to and parallelly-arranged with respect to said grid meshedopenings.

`HENRY JOSEPH ROUND.

